Swage for nesting 1/2" emt conduit

[forhire]

My friend came down today and wanted to build a swage for nesting 1/2" conduit. This has been on the list of things to have for a few years. Sure, he could have bought swaged pipe... but nobody locally stocks it. I've run into this a few times in the past when hanging fabric ducting... now we can make a piece anytime and any length :cool:

Found a piece of scrap and a few hours later had this tool.

The tool is simple, didn't want to spend too much time in case it not work. Currently the process takes two pressings. The results are way better than expected. Does anyone have any suggestions to make one that can do it all in one press?

Pic 1: Face the stock. It was 2" thick and 3" wide by 4" long.
Pic 2: Drilled a 19/32" hole through the block.
Pic 3: Chamfer the hole a little.
Pic 4: Drilled the holes for the alignment pins.
Pic 5: Welded the block unto a piece of scrap to facilitate cutting on the band saw.

More pictures on the next post :)

[forhire]

Pic 1: Cutting part on bandsaw
Pic 2: Cut part
Pic 3: Finished swage with pins installed.
Pic 4: Conduit after first press
Pic 5: Second press. Note the washers to help gauge the final dimension (due to saw curf)

[forhire]

Pic 1: Finished end. Sorry for the fuzzy photo.
Pic 2: Test fitting the two pieces of conduit.

[aevald]

Hello forhire, I have swaged various pipes and conduits using a hydraulic hose crimping machine. Fortunately for me I was able to pick up a portable hand-operated crimping press really cheap, I believe it is a Parker-Hannifan unit. They use die-sets that have vulcanized rubber that holds the pieces together for the two halves, I believe there are 4 sections for each die half. You can slip your part into these and then press them in one shot and reduce the diameter so that it can be slipped into another piece. This is accomplished by having the die tapered and round and the receiver piece is also tapered and round, as the die is pushed into it's mating female part it causes the inner diameter of the unit to be reduced. Your set-up is very cost effective comparibly and even though it takes two reductions it looks like it gets the job done nicely. Since it is always easier to see different ways of doing things once they have been done, here would be a suggestion for a slightly different approach to your design; drill your dowling holes prior to doing any machining, then cut the block in half, using the 4-jaw to hold the two halves together, machine the center hole last, thus you won't need washers to space the unit. Please don't take this suggestion as a criticism, I like your work, simple and effective. Best regards, Allan

[forhire]

Thanks Allen. No criticism taken. After making the part it became very clear it was done out of order. Experience is my best teacher.

[DSW]

Interesting. I'd expected you to make a swage to open up the emt rather than close it up. Guess thats because I'm used too working with copper pipe. I was thinking more of a tool like the ones shown that are usually driven into the end to expand copper to make a socket joint for soldering. With some you need to anneal the pipe a bit to make it easier to expand the tube.

Looks like you idea works fine.

[daddy]

Why would you do this instead of using a coupling with the set screw?

I'm asking because I don't know, not to be a smart azz.:waving:

[forhire]

Interesting. I'd expected you to make a swage to open up the emt rather than close it up. Guess thats because I'm used too working with copper pipe. I was thinking more of a tool like the ones shown that are usually driven into the end to expand copper to make a socket joint for soldering. With some you need to anneal the pipe a bit to make it easier to expand the tube.

Looks like you idea works fine.

The emt conduit has a tendency to split when expanded. The pipe is galvanized so we didn't want to anneal it and damage the coating any more than possible.

Why would you do this instead of using a coupling with the set screw?

I'm asking because I don't know, not to be a smart azz.:waving:

Those couplers, especially the steel ones may have worked. This method gives us a longer engagement at the junction and hopefully a stronger joint.

This is what they sale at the farm supply. It's designed for hanging curtains. They want $5.90 each. I can buy conduit for $1.97 each. At $4 savings it doesn't take long to make wages :laugh:
http://www.qcsupply.com/qcsupply/browse/productDetailWithPicker.jsp?productId=90258

[RancherBill]

Cool project.:cool2:

Soon you'll be supplying HF will HEAVY DUTY Engine Stands. :eek:

Seriously, there a ton of projects that this would be perfect. A small 8x10 green house comes to mind. Easy to assemble and disassemble. Hey, you could do a proof of concept greenhouse and send it to ME! :):)

All you need is a tubing bender and my greenhouse will be on the way.

[MoonRise]

Interesting project. :drinkup:

Yeah, I would have said the machining order should be:

- drill dowel holes;

- ream dowel holes for dowel press fit;

- split block in half length-wise with bandsaw;

- take one block half and ream the press-fit dowel holes into slip-fit dowel holes;

- press dowel pins into the press-fit holes;

-assemble the block using the dowel pins to align everything;

- put block into lathe and make the desired hole.

I obviously left out all the deburring and such. :laugh:

Idea to turn your tool into a one-shot and reduce/avoid the squeeze-out into the kerf/gap you currently get:

- add a protrusion into the die to press the tube/conduit inwards as the OD also gets pressed inwards.

Simple way would be to take a length of hard welding filler or drill rod of the appropriate diameter and then carefully weld it length-wise down the hole in the die. As you squeeze the tube/conduit, the 'ridge' contacts the OD of the tube/conduit first and presses it inwards making the 'crimp/dimple' and then the main hole in the die squeezes the OD of the tube/conduit down to the desired new OD size.

[jdh239]

Having a hard time picturing how it actually works. Any video?

[forhire]

Simple way would be to take a length of hard welding filler or drill rod of the appropriate diameter and then carefully weld it length-wise down the hole in the die. As you squeeze the tube/conduit, the 'ridge' contacts the OD of the tube/conduit first and presses it inwards making the 'crimp/dimple' and then the main hole in the die squeezes the OD of the tube/conduit down to the desired new OD size.

I laid some drill rod in the die. It didn't work as expected, it flattened the pipe too much.

I'm thinking I can cut a groove in the top of the die and put a plate in the groove the protrudes above the die, then when pressing this plate will indent the center of the conduit a bit before the die halves start.

I fixed the die this morning. It was simple enough to re-check it in the lathe and bore it to diameter. I then used an adjustable hand reamer to bring the die to the correct finish diameter after a few test parts. Now the fit is nice and snug and no pesky washers to deal with :cool:

[forhire]

Having a hard time picturing how it actually works. Any video?

I've uploaded a video here:
http://home.lewiscounty.com/~forhire/emt_conduit.wmv

Enjoy :D

[forhire]

There are many good ways to make duct. What is the easiest way to do this?

I assume you are referring to fabric air duct? If the duct is on a winch system you'll run a line through the duct and tie it to the conduit every 8 or 10 feet. The conduit supports the duct from the bottom and gives the tube some rigidity, especially when not inflated. We have used pre-swaged pipe, swages our own, and even used steel emt couplers.

I originally made this swage while making some chicken tractors. I can build a 10x12 tractor for around $20 in materials. :p

[ThorsHammer]

I'm not seeing a way to make this a single press system.

The drill/plate ideas have a fatal flaw, they fill the dimple with another material, thus preventing the pipe from filling said dimple and reducing the diameter of the pipe.

the current set up dimples out making "wings". it would be awesome if you could come up with a way to either shear, or fold over the wings in your first pressing. but I'm lost on how to accomplish this.

Now, onto the tractor, what is the approximate weight? how easy is it to move with 1 person? how much would you sell one for?

[ThorsHammer]

If you've got a mill, and could bevel an edge onto one half starting with the point at the edge of your bored hole, and sloping away from it. then mill out an area for the "wings" to fall into, you may be able to get the desired single press effect.

This leaves me with two concerns though. 1) is the swage made out of hard enough metal to cut the conduit without deforming. and 2) will the conduit retain the swaged shape if the wings are cut off.

I'm not sure you'd have enough room next to your hole to cut the bevel, and have the valley for cut metal before your guide pins on your current set up.

[forhire]

The drill/plate ideas have a fatal flaw, they fill the dimple with another material, thus preventing the pipe from filling said dimple and reducing the diameter of the pipe.

Yep. I tried that and it didn't work.

the current set up dimples out making "wings". it would be awesome if you could come up with a way to either shear, or fold over the wings in your first pressing. but I'm lost on how to accomplish this.

I'd rather not shear anything... I need the strength. A commercial die would fold it in and then press it round. I can be done... but not with such a simple die.

Now, onto the tractor, what is the approximate weight? how easy is it to move with 1 person? how much would you sell one for?

It's really easy with two people but very doable with one. I'd have to weigh some conduit to get a guess at the weight. I've thought about putting wheels on it. Sent PM about sales.

[ThorsHammer]

The only other thing I can think of is a die that pressed onto the conduit from the end. running a dimp up the conduit, then clamping down and pulling off shrinking the conduit as it comes off. it would be a total redesign, and I'm not sure that it would work without tearing the conduit.

You're probably better off sticking with the two step system.

[forhire]

Commercially this would ideally be done with a rotary swage like this:
http://www.youtube.com/watch?v=3YeItz_9bf8

[Rhinodaddy]

Try looking at the problem a little differently. An old timer I knew made a swaging tool for a lathe that was basically a roller ball mounted on the end of key stock. He mounted this ball/key stock where the cutting tool normally mounted, then he chucked the tubing into the lathe. Instead of turning the tubing down, he was shrinking it in by gradually increase pressure from the roller onto the pipe.

Two things to keep in mind. One is, the pressure on the tube is going to deflect it away from the roller tool somewhat, so you need to keep checking your true OD. The other is to keep in mind that your swaged tube is going to elongate a bit. Good luck.

[ThorsHammer]

I wonder, would it be possible/safe to make the roller ball attachment something that the pipe goes through instead of just something that it pushes against? that would eliminate the deflection.

The elongation would be minimal, and moot, as it would slide into the other piece of conduit. as long as your doing your measurements off where the taper starts, and not the overal piece you're good to go.

However, this does seem like it would take longer than running it under the press twice...

[AndyA]

Maybe take one of those scissor-type knurlers and just use smooth rollers. Keep tighening the scissor after each pass of the carriage. I don't know if pressure on only two sides would be enough to make it shrink, or if it'll just squish it in a rolling egg shape without shrinking any.

Definitely seems like it would take longer than the two-hit press method.

[Oldiron2]

Try looking at the problem a little differently. An old timer I knew made a swaging tool for a lathe that was basically a roller ball mounted on the end of key stock. He mounted this ball/key stock where the cutting tool normally mounted, then he chucked the tubing into the lathe. Instead of turning the tubing down, he was shrinking it in by gradually increase pressure from the roller onto the pipe.

Two things to keep in mind. One is, the pressure on the tube is going to deflect it away from the roller tool somewhat, so you need to keep checking your true OD. The other is to keep in mind that your swaged tube is going to elongate a bit. Good luck.

What you're talking about is called "metal spinning" and is explained a bit here:

http://en.wikipedia.org/wiki/Metal_spinning

Here is a link to what it typically looks like: http://www.winward.co.uk/metal%20spinning.jpg

Forhire's project could probably be done on his lathe. I'd try an internal live-center type mandrel in conjunction with an outside roller, perhaps a multistep roller assembly or a single one at an angle, the center to keep the part straight and resist side bending near the point(s) of roller contact.


.

[forhire]

Try looking at the problem a little differently. An old timer I knew made a swaging tool for a lathe that was basically a roller ball mounted on the end of key stock. He mounted this ball/key stock where the cutting tool normally mounted, then he chucked the tubing into the lathe. Instead of turning the tubing down, he was shrinking it in by gradually increase pressure from the roller onto the pipe.

Interesting approach. I imagine it would work. I'll have to try it. I've closed tubes on the lathe using one of my metal spinning tools... same idea. Because of the fit the swage was the fastest least trouble method to make the parts. I don't think I can spin them as fast as I can press them... now you have me wondering.

I wonder, would it be possible/safe to make the roller ball attachment something that the pipe goes through instead of just something that it pushes against? that would eliminate the deflection.

I originally tried feeding the tube though a tapered hole on the lathe... it didn't shrink as hoped... galled a bunch even lubed. I wonder it 4 bearings mounted at an angle perpendicular to the pipe could be fed into the taper and shrink.

Maybe take one of those scissor-type knurlers and just use smooth rollers. Keep tighening the scissor after each pass of the carriage. I don't know if pressure on only two sides would be enough to make it shrink, or if it'll just squish it in a rolling egg shape without shrinking any.

It might work. I don't have a scissor knurler to abuse. I thought about taking the cutter out of my pipe cutter and cranking the handle slowly while spinning in the lathe. I image this would shrink the tube... the only issue is the small size... 1/2" at a time.

Forhire's project could probably be done on his lathe. I'd try an internal live-center type mandrel in conjunction with an outside roller, perhaps a multistep roller assembly or a single one at an angle, the center to keep the part straight and resist side bending near the point(s) of roller contact.

Generally the rotation of the work keeps it straight unless you get too aggressive or the material work hardens. Now I'll have to head back out to the shop and play a little. :p

[Boostinjdm]

What if you cut a slot in your uppper die. Press a strip through the slot to form the dimple. Then remove the strip and continue pressing.

[CosmicRambler]

Did you try the idea of expanding it instead compressing it, or was that just rejected out of hand??? Something along the line of a tail pipe muffler exhaust expander. HF sells them but I don't think in 1/2" size. Be interesting to see how that works, nice to have something that does it one way or the other.

That expander seems to work on tail pipes ok.

[Boostinjdm]

Did you try the idea of expanding it instead compressing it, or was that just rejected out of hand??? Something along the line of a tail pipe muffler exhaust expander. HF sells them but I don't think in 1/2" size. Be interesting to see how that works, nice to have something that does it one way or the other.

That expander seems to work on tail pipes ok.

Have you ever used one of those? They don't work worth a ****. I've tried several and they all broke before the tube got big enough. They work for making pipes round again and that's about it.

[papaharley03]

Have you ever used one of those? They don't work worth a ****. I've tried several and they all broke before the tube got big enough. They work for making pipes round again and that's about it.

I've seen others that say the same thing about those. Someone mentioned heating the pipe a bit before using the expander. I may pick one of those up just to see what others are talking about.

Preheating seems like an idea though.

[papaharley03]

Forhire, I am thinking that in order to achieve a dimple as the die halves press together, you need to have a somewhat sharp pointed lip where the halves meet. This should start the dimple inward, followed by the crimp as the halves meet.

I'm trying to draw it in Sketchup, but it's not behaving for me.

[papaharley03]

OK, got it drawn out. What do you think about this design?

[joebie]

Papaharley does that taper on the inside?

[RaptorDuner]

Have you ever used one of those? They don't work worth a ****. I've tried several and they all broke before the tube got big enough. They work for making pipes round again and that's about it.

I"ve used one to expand 2" pipe about an 1/8th to make an air to air heat exchanger for a boiler. Worked good for that but after doing both ends on 54 pipes it was ready to throw away. I can't imagine going any more than an 1/8th though. We adapted it to our hydraulic power unit and it still had a workout.

[little Jeep]

I've uploaded a video here:
http://home.lewiscounty.com/~forhire/emt_conduit.wmv

Enjoy :D

Thanks for the video...... :cool:

[papaharley03]

Papaharley does that taper on the inside?

No, it's consistent diameter. Not a proven design, just a concept that I thought would start an inward crease as the two halves come together with the pipe centered between them.

I used to use Amphenol 4 way crimp tools for the connector pins. They had sharp edges on the crimp die, which is part of the basis for my idea.

I don't have the capabilities to fabricate one to test it out, or I would.

Papa

[toby250]

OK, got it drawn out. What do you think about this design?

Like this,NO?

[papaharley03]

Like this,NO?

LOL, yes. I was just making that change in my drawing when you posted this. :D

[forhire]

What if you cut a slot in your uppper die. Press a strip through the slot to form the dimple. Then remove the strip and continue pressing.

This may work... and I've thought about doing it. The main issue is that the tube is larger than the die... so even pressing the center causes the sides to expand out of the die. I suspect commercially they are using a 5 part die and pushes the sides together as the center is collapsed and the finishes with the top half making final shape. Similar to a U channel die.

Did you try the idea of expanding it instead compressing it, or was that just rejected out of hand??? Something along the line of a tail pipe muffler exhaust expander. HF sells them but I don't think in 1/2" size. Be interesting to see how that works, nice to have something that does it one way or the other.

That expander seems to work on tail pipes ok.

Yes. The material thinned too much and tended to split. Remember we are talking about emt conduit.

Have you ever used one of those? They don't work worth a ****. I've tried several and they all broke before the tube got big enough. They work for making pipes round again and that's about it.

:eek: Well said!

I've seen others that say the same thing about those. Someone mentioned heating the pipe a bit before using the expander. I may pick one of those up just to see what others are talking about.

Preheating seems like an idea though.

I didn't want to heat the conduit and lose any more of the galvanizing than necessary. Also, I didn't want to soften the junction.

Forhire, I am thinking that in order to achieve a dimple as the die halves press together, you need to have a somewhat sharp pointed lip where the halves meet. This should start the dimple inward, followed by the crimp as the halves meet.

OK, got it drawn out. What do you think about this design?

I tried this already. Albeit not as fancy. Because the tube is larger than the die, the additional spread caused the pipe to flatten and not dimple. Boostinjdm idea of using a separate press center would likely work.

I"ve used one to expand 2" pipe about an 1/8th to make an air to air heat exchanger for a boiler. Worked good for that but after doing both ends on 54 pipes it was ready to throw away. I can't imagine going any more than an 1/8th though. We adapted it to our hydraulic power unit and it still had a workout.

In my last life... before moving to Morton... I was a boiler operator for a couple years. Tubes are roll expanded to ensure a air/water tight seal. In an air exchanger your exhaust expander would work but it's not idea as you discovered. Wilson makes some... I'm sure there are others. http://www.tcwilson.com/boiler_tube_expand/expanders/index.php

No, it's consistent diameter. Not a proven design, just a concept that I thought would start an inward crease as the two halves come together with the pipe centered between them.

I used to use Amphenol 4 way crimp tools for the connector pins. They had sharp edges on the crimp die, which is part of the basis for my idea.

I don't have the capabilities to fabricate one to test it out, or I would.

I tried tacking in some drill rod. It caused the tube to flatten rather than dimpling. I suspect to dimple the sides must be supported.

[RaptorDuner]

In my last life... before moving to Morton... I was a boiler operator for a couple years. Tubes are roll expanded to ensure a air/water tight seal. In an air exchanger your exhaust expander would work but it's not idea as you discovered. Wilson makes some... I'm sure there are others. http://www.tcwilson.com/boiler_tube_expand/expanders/index.php

We have the replacement tubes on the pressure vessel rolled into place but hire a contractor to that. Same contractor wanted $12k to do the air to air and we did it for $3200 inclusive.

I'm gonna play around with our hydraulic hose press to see how it works on the EMT.

[toby250]

This may work... and I've thought about doing it. The main issue is that the tube is larger than the die... so even pressing the center causes the sides to expand out of the die. I suspect commercially they are using a 5 part die and pushes the sides together as the center is collapsed and the finishes with the top half making final shape. Similar to a U channel die.



Yes. The material thinned too much and tended to split. Remember we are talking about emt conduit.



:eek: Well said!



I didn't want to heat the conduit and lose any more of the galvanizing than necessary. Also, I didn't want to soften the junction.





I tried this already. Albeit not as fancy. Because the tube is larger than the die, the additional spread caused the pipe to flatten and not dimple. Boostinjdm idea of using a separate press center would likely work.



In my last life... before moving to Morton... I was a boiler operator for a couple years. Tubes are roll expanded to ensure a air/water tight seal. In an air exchanger your exhaust expander would work but it's not idea as you discovered. Wilson makes some... I'm sure there are others. http://www.tcwilson.com/boiler_tube_expand/expanders/index.php



I tried tacking in some drill rod. It caused the tube to flatten rather than dimpling. I suspect to dimple the sides must be supported.

Yes, you are correct,bad sketch but something like this is sure to happen :eek:

[toby250]

Yes, you are correct,bad sketch but something like this is sure to happen :eek:

sorry didnt see the other replys

[forhire]

We have the replacement tubes on the pressure vessel rolled into place but hire a contractor to that. Same contractor wanted $12k to do the air to air and we did it for $3200 inclusive.

I'm gonna play around with our hydraulic hose press to see how it works on the EMT.

Oh yeah, I remember the big repair bills. :dizzy:

You can buy a roller expander off ebay for around $200... it's the drive unit that I'm not sure about. I wonder if you could drive the expander with an impact wrench?

Let me know how your crimper does. :D

[forhire]

Yes, you are correct,bad sketch but something like this is sure to happen :eek:

Thanks for the awesome sketch... you nailed the issue perfectly :)

[forhire]

Thanks for the video...... :cool:

I finally got a personal youtube account and uploaded the video here:

http://www.youtube.com/watch?v=NiWhyEFMAMk

[Oldiron2]

I'd prefer to shrink the end uniformly rather than having indented sections.

If you had a slight rounding of the edges where the die inside surface meets the break line, as would be formed by drilling two small holes on each side before boring the main cavity, then the excess metal can expand a bit into there as the die is closed. This might require a series of progressive dies, depending on the degree of reduction in diameter. If so, it would be best to have a hydraulic press with all dies installed at once so each tube could be put through all dies at one holding, rotating the tube to remove the bulge just formed when going into a smaller die and rotating one extra time in the last die.

That said, you need to do what works for you using available equipment, time and energy. :)

[toby250]

you could do something like this,machine out some pockets along the length of the tool and use flat plate to stop the wall of the conduit going outwards...

[ThorsHammer]

you could do something like this,machine out some pockets along the length of the tool and use flat plate to stop the wall of the conduit going outwards...

The problem with this design is it leave two areas where there is no connection with the other tubing section. this creates a couple problems. Area for water to get in/sit, and reduced surface area for friction fitted items. I don't believe forhire is drilling, taping, and adding set screws for each connection. The original one that the produced the wings limited this because the "dimple" was filled with the wing.

I think the best option is the rotary swage, this eliminates the dimple, and doesn't reduce the wall thickness.


I was thinking a three stage Swage. put the pipe in the lathe, and the swage is three set of three rollers that the pipe feeds through. The rollers have a beveled edge on them so as the swage gets slide over the end of the pipe it gradually gets smaller until the pipe end gets past the smallest edge of the last set of rollers.

Think three axles with three bearings on each, each bearing with a roller the first roller on each bearing is the smallest. With the bevel starting at the leading edge and going up (in when fully assembled) at an angle to the leading edge of the second roller, and the same for m the second to third, and the third roller's bevel ending (when fully assemebled) at the finished diameter of the desired pipe size.

I'm not sure what the size difference between the original and finished sections would be, but I think somewhere betweek 1/4 and 1/2 wide rollers should work fine. this would leave anywhere between a 3/4" beveled shoulder, and a 1.5" beveled shoulder.

I think that this is something that could be assembled by forhire. (access to both a lathe and a mill) the nicest part is you could have multiple diameters available to you if you keep the axles easily removeable.

[CosmicRambler]

What happens if you put the tubing back thru the die a second time with the wing thingee pointing directly up / down? Just wondering how that then tries to flatten out and does another one try to form. Would four lil bumps be better than two. Nice to get to see it in real form instead of some theory stuff.

[toby250]

id say water would get in no matter what you do and the loss of surface area for friction would be very small,its a solution for a one hit tool and he could just mod the one he has....

[AndyA]

Why not make a die with two holes side-by-side. The first hole is the same size as the original tube, but with strips to start the dimples. The second hole is the one that reduces the diameter and crushes the dimples. You might even design the first hole so that it intentionally egg shapes the tube just a little (makes the dimpled sides a little closer together). Then you can rotate it 90deg when moving to the second hole so it fits nicely in the reduced diameter. The dimples would be along the parting plane of the die and that may help solve any 'pinch out' problems.

[ThorsHammer]

Why not make a die with two holes side-by-side. The first hole is the same size as the original tube, but with strips to start the dimples. The second hole is the one that reduces the diameter and crushes the dimples. You might even design the first hole so that it intentionally egg shapes the tube just a little (makes the dimpled sides a little closer together). Then you can rotate it 90deg when moving to the second hole so it fits nicely in the reduced diameter. The dimples would be along the parting plane of the die and that may help solve any 'pinch out' problems.

the problem with that design is it takes a lot more force to force something through a hole than it does to compress it. not to mention that you'd need some sort of ram to get it to work.

[AndyA]

the problem with that design is it takes a lot more force to force something through a hole than it does to compress it. not to mention that you'd need some sort of ram to get it to work.

I was still talking about a split die that you use with a press.
Just do two hits. One to start the dimples and eggshape it a little. And the second to size it.

[CosmicRambler]

Why not make a die with two holes side-by-side. The first hole is the same size as the original tube, but with strips to start the dimples. The second hole is the one that reduces the diameter and crushes the dimples. You might even design the first hole so that it intentionally egg shapes the tube just a little (makes the dimpled sides a little closer together). Then you can rotate it 90deg when moving to the second hole so it fits nicely in the reduced diameter. The dimples would be along the parting plane of the die and that may help solve any 'pinch out' problems.

Yeah that might be a great approach. Two passes or even three if that is what it takes. Ye olde progression.

Could just work and he has the ability to make one. With enough tries you always come up with a solution.

[ThorsHammer]

thats essentially what he has, the only difference is it has wings instead of dimples. He's looking for something to do it in a single step. instead of two.

[papaharley03]

And there's nothing that says it has to be two dimples. Could go with just one.

Plus, I think that a sharp point like I illustrated is better at starting a dimple than a rounded dimple surface.in the die.

[forhire]

Ok, I messed around with this a little tonight. First I retrofitted a two wheel knurling tool with two small bearings. The knurling tool defects the pipe too much and has little results. Supporting the tube with a live center made it impossible to shrink the end and an attempt to shrink in the middle, while it appeared to work somewhat, it belled the end like a horn.

Next I removed the cutting blade from a pipe cutter and replaced it with a bearing. Initial tests by hand suggested it might work. In the end the conduit became square. I thought maybe I had gone too quickly so I mounted the cutter in the tool post and went at it. Even after a few passes it was clear it was going to be square. I now know how to make square tube. :dizzy:

I suspect that the pressure from the single roller against the two rollers made a flat spot and as the tube shrinks it becomes more pronounced. Maybe squeezing with one roller opposite another may work... sounds like the scissor knurl idea :confused:

Don't bother giving me grief about the chuck jaws. I've been facing large rounds today and more of the same tomorrow... I didn't want to change my setup for a quick test. :eek:

Well... now I know what doesn't work. :)

I snapped a couple pictures. Enjoy :D

[ThorsHammer]

I wonder if having the three rollers evenly placed would help?

[forhire]

I wonder if having the three rollers evenly placed would help?

I don't think so. The lower single roller is pushing straight up creating a rise between the two upper rollers, eventually leading to square shape. Two rollers on the bottom equal to the two uppers might do the trick.

[ThorsHammer]

so two total, or 4 total?

[forhire]

so two total, or 4 total?

Two might work... four would likely be better... all I know is three makes squares :p

[ThorsHammer]

three wheels to compress it = how to fit a round peg into a square hole.

[dumb as a stump]

Ya know I am thinking that what you are looking at doing is very much like making a tent pole, for an older type tent. Perhaps looking at one may provide some light on the subject. I am watching this because i have had a desire for the exact same thing but dont have the gear to machine etc. I know that our local electrical suppliers carried 2 inch swedged emt (about 5 years ago when I saw it as a new product) but nothing smaller. I thought it was a great idea at the time.

[Oldiron2]

During metal spinning, the speed it usually fairly high, the point of contact is quite small and a small area of the surface is deformed by just a tiny amount each revolution, but because of the high speed and many resulting revolutions, the shape does gradually change. In your test, due to the large rollers you were just bending the whole surface. Didn't mean it would be easy, but do still think it can be done with your available equipment.

I also agree with earlier members who think expanding the end would be easier. If the tool is properly made, the forces are spread around the entire inside, not concentrated in one place, so splitting won't occur. It is easier to stretch then to swage into a new shape.

The most fun way might be to build a one piece outside die of the required shape into which the tube fits, insert a mechanical stop into the tube above the area to expand but within the die still, add a bit of mud, then an electrical blasting cap, then more mud, ....."Fire In The Hole" and it's done except for removal and cleaning.... Oh well,,,

The standard multi-piece inside die with a tapered hole, a tapered bolt or rod, and perhaps a hydraulic cylinder attached to the rod to work it isn't that hard to machine, but should have hardened insides to reduce deformation and thus friction. An alternative material might be 'hard' but still flexible rubber just compressed by a bolt, or a variation with a tight bronze seal at the operating end and a viscous liquid inside the hard rubber sleeve....

Or suppose you had a mandrel mounted on the lathe carriage with a few hardened pockets for small bearing balls, perhaps tiny lubricant/coolant passages running to the bottom of each from the tool's rear end so the fluid could be fed under decent pressure; then the carriage could be fed into the tube under power. A fine feed, rolling balls and small contact area should allow the micro-deformation while the lube would prevent galling of the tube and stop wear of the ball or pocket. Maybe add screwed-in bottom plugs to adjust the protrusion of the balls in the pockets.

BTW an external version to reduce the tube could be made, I suppose.


"Just thinking out loud."

[forhire]

I tried spinning a piece tonight. Understand I'm no spinning expert but I've done a fair share. The conduit was too large to fit through the spindle of my spinning lathe (I also don't have a three jaw chuck on that lathe either) so I did a quick test on the Lablond, which lacks the rpm and the pin post of the spinning lathe. One thing that came out of the test is that the material will need to be annealed (which I did part way through) and the weld seam is a problem. As soft as emt appears... it's not. The weld seam is hard. Definitely not fast. I'm not really interested in spinning the quantity required. Remember, I built this swage to save time and money.

See how the conduit creased at the weld. The weld may have been the root cause of the square shrink yesterday :p

[RaptorDuner]

I had good results with 1" EMT in our Aeroquip Procrimp 1380. The smallest die we have (#4) doesn't quite get it small enough.

[forhire]

I had good results with 1" EMT in our Aeroquip Procrimp 1380. The smallest die we have (#4) doesn't quite get it small enough.

I unzipped the images and attached them.

Looks great! I actually expected the crimp to have ridges similar to a hose... but it looks round. The results actually look better than expected. :cool:

[ThorsHammer]

but it's still not small enought to go into the un crimped end? can you get a smaller die?

[forhire]

but it's still not small enough to go into the un crimped end? can you get a smaller die?

I'm sure you could get/modify a die to get the diameter desired. I don't foresee a hydraulic hose crimper in my near future... I have other tools on my wish list. ;) I've attached what the die looks like. RaptorDuner was kind enough to test it with his machine just to see if the segmented static die would work or if it had to be a rotary swag. :cool:

RaptorDuner, this is a #10... does it look the same as your die?

[AndyA]

I wonder if you could make a collet style crimper? Have maybe 6 or 8 fat slots cut into it to allow plenty of shrink.
Perform the crimp using threads to draw the collet down into a female tapered piece.
I don't know what pitch you'd want to make the taper. A slight angle should give you more force, but may be more likely to get stuck.
You might want acme threads and a thrust bearing on the closer nut since this may take quite a bit of force to shrink the tube.

This could probably also be adapted to use a hydraulic pull cylinder instead of threads to tighten the collet.

[RaptorDuner]

Looks just like that. Our smallest die is a #4 and doesn't quite get 1/2" EMT small enough. The 1" EMT is actually undersized a little too much and fits quite loosly. Our crimper is programmable so with some messing around to find the right preset, you could get a perfect crimp everytime. A #2 die may be available but we don't have a need so I don't see us getting one to do 1/2" EMT.

One note: while crimping I would crimp about 3/4 of the way and back off slightly and turn an 1/8th of a turn and finish. Adds literally 2 seconds at most. If I didn't turn it, it might get better traction in the joint with the small "wings" it would leave. Might have to try that Monday.

We don't actually own this crimper. It's provided by Applied Industrial because we buy hydraulic fittings from them. Forhire, you could contact them and say you'll buy from them if they provide you a crimper.:D

[fred_dot_u]

Even though this is an older thread, I'd like to join in and comment on AndyA's suggestion. The way I read it is to have two slots, not holes, in the block. One slot is the tubing diameter with a wedge at the top and bottom, with the vertical diameter of the joined blocks to be less than the stock diameter. The tubing would dimple as desired and would remain within the block.

The second slot in the block would resemble the original design, with respect to diameters, but would not have to deal with the spread of the tubing outside of the slot, as it would be the correct finished diameter from the above step. It would be necessary to rotate the tubing ninety degrees in order to place it in the slot, but instead of spreading the tube as the upper part is pressed on, the dimples would compress that much more.

If this is an incorrect interpretation, I'm open to constructive criticism.

If someone is already building one of these, please let me know. My searches online have all petered out, except for this one. It should not require thousands of dollars of hydraulic equipment to crumple ordinary EMT, in my opinion, and this particular thread shows that to be true!

fred

[zipzit]

I know this is a pretty old topic, but I really like interesting engineering problems.

I'm pretty sure forHire has a full size lathe. Not sure, but I suspect he has access to a hydraulic press. How about a cone shaped die and nest? Easier to show you then explain.

I'm assuming a pipe nipple placing force on the ends of the die, forcing them into the nest around the pipe to be compressed. The seven degree angle on the die mates to the 7 degree angle in the nest (in theory) compressing the tube OD smaller.

Assumptions: nominal conduit 1/2" OD=0.840, ID=0.632
Not sure how big your lathe chuck is, I just grabbed 5x5x3" stock for the nest, 2" thick x 3" diameter stock for the die(s). I assumed you'd turn the inner die(s) on the lathe, then cut into fourths with a band saw. I used a 7 degree cone shape. No reason for that number, I just pulled that number outta... the air. The four die pieces complete their motion when bottom of die(s) is flush with bottom of nest.

One problem could be how long the tubes are.. If too long, you'd have to rotate the press sideways and thats a major pain.

comments?
--zip

[fred_dot_u]

I like the simplicity of the cone press method. EMT can be as long as ten feet (50 toes) and would not work well in most presses, I suspect. One reason to perform this swaging is to make longer lengths from stock pieces.

Regardless of the method, dual slot, single slot, cone-press, I envisioned a lever system for my own use, just a ten foot length of pipe pushing down on a short fulcrum to provide quick action and high forces necessary to make the swaging. It would be just as simple to make the lever arm swing sideways, perhaps easier on the back to do so.

I'd want six inch swaging, so a six inch tall block would do the trick.

Before the four sections of the cone come fully together, would the tubing dimple into the gaps and prevent proper forming?

[forhire]

Good ideas. The taper needs to be fairly steep or you'll never get it apart... I'd go with 15 degrees or better at least. Zip were you thinking 7.5 total or per side? I like the hand idea.

I have a couple lathes... wouldn't take long on my cnc. :)

[fred_dot_u]

Fairly steep meaning closer to parallel or in the other direction, as in closer to 45 degree sides?

How would one consolidate the four cone segments to allow semi-production performance? Add guide pins pm the top of the cone segments that engage a slot on the plate that does the pressing into the die? That doesn't sound right, now that I've typed it out here.

I would look for something to attach either part to a lever, with the other part on a fixed base. Grab the long lever, push it open, slide in the tubing, pull the lever closed, then open to remove. Horizontal movement as noted above.

Four loose cone segments would fall out when the lever was opened, but then again, it would not have to open very far to release the tubing.

[forhire]

I should have said fast instead of steep. ;)

I'll have to measure the angle on one of the hydraulic dies in the morning. My guess the are 30 degrees.

[zipzit]

I made the cones using the Autocad Extrusion tools at a 7 degree angle (at each 'side'.. times 2 = 14degs) The inner cone was 3" OD at the base of the cone, and the outer nest is 3.5" ID at the base of the cone shaped hole. No reason to use those numbers.. they just felt about right. .

[fred_dot_u]

it sounds more like the TLAR method, which often works quite well in matters such as this. (That Looks About Right)

What do you think will happen to the tubing as the cones are brought down or into it? Will the gaps become wedged with tubing or will it dimple inward as desired? I'm thinking the former, based on earlier posts in this topic.

If the inner bore of the cones had a ridge on each, centered lengthwise along the radius, it might dimple as desired, but it would make the production of the cones that much more complex.

[forhire]

What do you think will happen to the tubing as the cones are brought down or into it? Will the gaps become wedged with tubing or will it dimple inward as desired? I'm thinking the former, based on earlier posts in this topic.

If the inner bore of the cones had a ridge on each, centered lengthwise along the radius, it might dimple as desired, but it would make the production of the cones that much more complex.

With the full diameter die you have to press, rotate, and press again. You won't have any dimpling like you see in the two part die because you'll get a more uniform shrink. Look at the examples that raptorduner posted. No need to dimple if you control the shrink.

Understand that the two part die works great and I've done hundreds of pieces with it. At nearly $4 per piece savings it has more than paid for itself. Of course I'm always looking to speed up production. :D

Zipzip, I got your email. Here's my rendition... solved the holding it all together with an o-ring... and keeping them separate with some rubber rod. Might have to machine some flats along the rod bores to provide some space for squish. Or maybe machine a shallow radius rather than drilling a hole. Often I crank out the drawings and then let the idea simmer for a few days.

I drew this a revolved boss... I find for turned work it's faster to visualized the profile... as I'm going to have to setup the machine using the profile anyway. ;) Of course I extruded my cuts and such. I don't know if Acad does revolved surfaces.